The present invention generally relates to integrated circuit structures and more particularly to a structure and process that reduces capacitance of organic insulators by forming pores between the insulators and the liner that lines conductive features.
Recent technological advances in integrated circuit design include the use of insulators (dielectrics) that have a lower dielectric constant (and are softer) which are replacing older, harder, higher dielectric constant insulators. Lower dielectric constant materials generally include organic low K dielectrics commercial products, such as SiLK, available from Dow Chemical Company, NY, USA. These lower dielectric constant insulators are referred to as “low-k” dielectrics. These low-k dielectrics are advantageous because they decrease overall capacitance, which increases device speed and allows lower voltages to be utilized (making the device smaller and less expensive). Such low-k dielectrics have substantial and well-documented advantages over previous high-K dielectrics.
Additional progress has been made with low-k dielectrics by utilizing the porous form of such dielectrics because the porous forms of such dielectrics have reduced capacitance. However, a problem exists when using porous low-k dielectrics because the material used to line trenches and vias often fills the pores along the sidewalls of the trenches and vias. This reduces the effectiveness of the porous dielectric and can also result in defects if enough liner material escapes into the porous material. The invention described below overcomes these problems through a new structure and methodology.